Tower for a Wind Power Installation

ABSTRACT

The invention relates to a tower for a wind power installation, wherein the walls of the tower are at least partially produced from individual wall sections which are connected to one another by means of connection means. The object of the invention is therefore to provide a tower which can be assembled with a sufficient degree of precision. It is also the object of the invention to provide a method for erecting a tower of this kind. The object according to the invention in respect of a tower of this kind is achieved in that an empty framework is at least partially provided in the interior of the tower and the wall sections are retentively connected to said empty framework.

The invention relates to a tower for a wind power installation wherein the walls of the tower are at least partially produced from individual wall sections which are connected to one another by means of connection means.

A wind power installation is an apparatus for generating electric energy. The wind power installation is provided with a foundation, a tower which is constructed on the foundation and a nacelle which is arranged on the tower. The drive unit connected to rotor blades is situated on the nacelle for generating energy.

The structure of the tower is oriented to the static load generated by the nacelle on the tower and the dynamic loads generated by the rotation of the rotary blades of the rotor and by the movement possibility of the nacelle in dependence on the direction of the wind. Known towers are produced from steel rings or concrete elements. The bases of the known towers, in this case, are either polygons or ring-shaped circle segments. Polygonal towers, which are produced from individual concrete segments, are known from WO 2003/069099 A. In addition, constructing such polygonal towers from timber is known (DE 10 2007 006 652 A1).

Looked at from an economic point of view, it is desirable to construct the height of the towers in an economically maximized manner as the return of a wind power installation depends on the hub height of the rotor and the return increases as the height increases. At the same time the demands on the statics and the material of, or the material outlay on, the tower created by the greater height of the tower increase. The wall thicknesses increase and this means that the costs of constructing the tower increase.

An aspect which is critical in the process in the case of towers which are formed from segments which are arranged in sections is that the horizontal contact surfaces of the segments which are arranged one above the other are sensitive to shear loads and lateral forces. This has to be taken into consideration in the statics of the towers, so that this predetermined breaking point is neutralized, this leading to an increased use of material, and in particular requires the use of complicated connection means.

Consequently, it is the object of the invention to provide a tower for a wind power installation, where it is possible to increase the height of the structure and at the same time to save on material and/or to reduce production costs while taking into account the abovementioned lateral force or shear load problems.

The object according to the invention is achieved in that the wall sections are arranged in a manner offset in relation to one another so as to form a helix. As a result of this relative arrangement, the shear load/lateral force is dissipated over the helix and there is no starting point for the tower to lift off at a predefined point. Therefore, wall thicknesses can be reduced and it is possible, in particular, to select simpler and therefore more cost-effective connection means.

A further teaching of the invention provides that the helix is a simple helix or a multiple helix which is formed from a plurality of simple helices. In the case of a multiple helix, it is advantageous for the number of simple helices which form the multiple helix to correspond to the number of wall sections in a horizontal plane of the tower. In the case of the multiple helix, the wall sections are preferably provided as a rhombus which is placed on end. In this case, the rhombus is provided as a circle segment or is formed by two triangles which are connected to one another in a vertical manner, wherein the surfaces of the triangles are arranged at an angle relative to one another of 360° divided by the number of simple helices. It is further advantageous for the upper joint sides of the individual components of a helix to have a continuous line and/or a graduation. As a result, load dissipation in the tower is improved.

A further teaching of the invention provides that the wall sections at least partially in the joints have slots which are arranged transversely to the direction of the joint and/or along the direction of the joint. Connection means are preferably inserted into said slots, said connection means in a preferred manner being metal plates, in a particularly preferred manner perforated plates which are preferably bonded. In addition, the joint openings can be masked for example with a tape or Plexiglas. The insertion of the adhesive is preferably effected by means of injecting the spaces between component and connection element. As an alternative to this, wood parts or wood dowels can be used when the components are timber elements. These connection means are cost-efficient elements which, however, provide the necessary strengths with regard to shear or shear loads between the individual components.

Apart from the operating stresses which act on the tower, climatic stresses also act on the tower. In the case of steel towers, this climatic stress is counteracted by applying a coat of paint onto the tower. Where reinforced concrete is used, the steel framework absorbs the tensile stresses of the tower. The concrete covering absorbs the pressure loads and at the same time serves to protect the steel structure against environmental influences in the form of moisture and chemical reactions caused by the surrounding atmosphere. The thickness of the concrete has to ensure that the steel framework is protected from these loads. In the case of timber structures, corresponding meteorological stresses are counteracted by coats of paint. At the same time, it is only possible to use timber materials that are authorized for exterior use for the construction of timber towers.

A further teaching of the invention therefore provides that a coating is applied at least partially onto the exterior surface of the tower, the coating preferably being applied such that the coating absorbs tensile stresses which act on the exterior surface of the tower, and that the coating seals the exterior surface of the tower against environmental influences, in particular humidity, which act on the surface from the outside.

With reference to steel towers, a coating of this type makes it possible to reduce the amount of steel necessary with regard to tensile stresses as the coating absorbs tensile stresses, and at the same time to save on the painting of the steel elements. With regard to concrete towers, it is possible to reduce the concrete covering over the steel framework such that there is a reduction in costs. With regard to timber towers, the coating makes it possible to use timber materials and their connection means that are only authorized for interior use.

A further teaching of the invention provides that the coating is applied over the entire surface in the coated section of the tower and covers the coated section. In this case it is advantageous for the coating to be a laminate, a foil, a woven fabric, a textile or a plate. In a particularly preferred manner, it is a foil, a plate, a woven fabric and/or textile produced from plastics material, wherein, in a particularly preferred manner, polypropylene, polyurethane, polyvinyl chloride, polyester, polycarbonate or polythene are used as the materials. Such materials are capable of absorbing tensile stresses and at the same time provide a closure and consequently a seal against the environmental influences which act on the surface of the tower. At the same time, such materials have a lower weight per surface area than, for example, coats of paint on the surface of the tower such that this weight is able to be reduced in the structure with regard to the static pressure load, as a result of which the tower structure is able to be designed overall in a more slender manner. At the same time, the costs of said materials are lower than, for example, coats of paint.

A further teaching of the invention provides that the coating is applied at various points during the constructing of the tower. The coating is applied once the tower has been constructed as the first variant. This can be effected from the top or bottom. As an alternative, the coating can be applied in sections during the construction of the tower or can be applied onto the individual components even before the tower is constructed. If the coating is applied before the tower is constructed, it has proved advantageous for the coating to be applied on site at the place of construction. This reduces the costs of the coating and at the same time it can be ensured that the coating is not damaged when the individual elements are being transported. The individual sections of the coating are subsequently connected together, wherein, in a particularly preferred manner, the connecting is effected by bonding or welding the joints.

A further teaching of the invention provides that the coating is applied directly onto the components of the tower. In a preferred manner, the applying is effected over the entire area by means of bonding. As an alternative to this, bonding can also be effected in sections to a surface of a component. The bonding ensures that the static load is absorbed by the coating.

A further teaching of the invention provides that the tower is constructed at least partially from steel, concrete, in particular reinforced concrete, and/or timber or wood material. The timber or wood material is preferably laminated plywood and/or wood composite materials.

A further teaching of the invention provides that the vapor permeability of the coating is less than that of the timber. In this way the diffusion is reversed, i.e. the vapor permeability of the tower is not increased towards the outside, but towards the inside. In addition, in a preferred manner, a heat generator is arranged in the interior of the tower, wherein, in a preferred manner, this is the power electronics of a wind power installation. In this case, the heat is the power lost from the power electronics. The generation of heat causes the moisture located in the interior of the tower to be removed upwards and the moisture emerging from the timber to be moved towards the interior of the tower and then also removed upwards. If the coating is damaged, removal of the moisture inwards is ensured. Through the particles and minerals located in the moisture, the damage to the coating is gradually closed and at the same time it is additionally ensured that the moisture escapes towards the inside.

A further teaching of the invention provides that the support structure of the tower is constructed at least partially from materials which are not suitable for exterior use. In this case these are materials which have been authorized simply for interior use in the construction of buildings. The applying of the coating makes it possible to use these types of materials and also connection means for the support structure of a tower for a wind power installation because the coating ensures the state of interior use for the materials.

A further teaching of the invention provides that the tower is assembled on site from individual components. The components assembled on site are plane elements.

Assembling the tower in this manner from individual plane elements ensures that the transport cost of the individual towers is reduced in a considerable manner.

The invention is explained below by way of preferred exemplary embodiments in conjunction with a drawing, in which, in detail:

FIG. 1: shows a three-dimensional view of a wind power installation with a tower as claimed in the invention,

FIG. 2: shows a three-dimensional view of the tower as claimed in the invention,

FIG. 3: shows the sides of the tower as claimed in the invention arranged next to each other,

FIG. 4: shows an alternative embodiment of the tower as claimed in the invention,

FIG. 5: shows an alternative embodiment of the tower as claimed in the invention,

FIG. 6: shows an alternative embodiment of a tower as claimed in the invention,

FIG. 7: shows an inside view of the wall elements in FIG. 6,

FIG. 8: shows a three-dimensional view of a base element of a further alternative embodiment of the tower,

FIG. 9: shows a three-dimensional view of the constructing of a tower in FIG. 8,

FIG. 10: shows a three-dimensional representation of a connection means as claimed in the invention,

FIG. 11: shows a view of a detail in FIG. 10,

FIG. 12: shows a finished mounted view of FIG. 10,

FIG. 13: shows an alternative connection possibility,

FIG. 14: shows a sectioned view of a detail in FIG. 13,

FIG. 15: shows an alternative connection possibility,

FIG. 16: shows an alternative connection possibility,

FIG. 17: shows a top view of FIG. 16,

FIG. 18: shows a method for applying a coating,

FIG. 19: shows a side view of a coated tower wall,

FIG. 20: shows a side view of a wall structure as claimed in the invention,

FIG. 21: shows a side view of an adapter for fastening a nacelle to a tower as claimed in the invention,

FIG. 22: shows a top view of the underside of the connector,

FIG. 23: shows a first embodiment of an adapter as claimed in the invention and

FIG. 24: shows a second embodiment of an adapter as claimed in the invention.

FIG. 1 shows a wind power installation 30, which consists of a tower 31 which stands on a foundation 32, and a nacelle 33 which is connected to the tower 31 by means of an adapter 35. A rotor 34, which has rotor blades 36, which are connected to the nacelle 33 in a hub 37, is provided on the nacelle 33, which is horizontally rotatable.

Different embodiments of the tower 31 are represented below.

As shown in FIG. 2, the tower 31 has an exterior side 38. The tower 31 is realized as a polygon. In the present case this is a hexagon, other polygons, such as a tetragon, pentagon, octagon, decagon or dodecagon or larger are equally easily possible. The same also applies to a circular cross section. The tower 31 in FIG. 2 has six tower sides 39 which, over their whole surface, can be realized in a conical manner. The tower sides 39 are formed from individual wall elements 40 which, where applicable, have a shortened wall element 41 on the bottom side and 42 on the top side. In the embodiment in FIG. 2, the wall elements 40 are realized as a tapered trapeze, wherein the individual wall elements can be assembled together from different part elements. The embodiment in FIG. 2 has a helical structure. This can be seen in FIG. 3 where the six sides are shown next to each other. In this case, the individual wall elements 39, from side to side, are arranged offset in relation to each other always upwards by a sixth of the wall height, wherein, in this case, the dimensions of the individual wall elements 40 have been taken into consideration corresponding to the tapering of the individual tower sides 39. The six wall elements, in this case, form a helix section 43. This design ensures that the seventh-following wall element is arranged directly on top of the first wall element and these two wall elements stand one on top of the other on the side of the joint. In the case of other polygons, the offset is 1/n* height of the wall element 40, wherein n is the number of polygon corners. These specifications also apply to the embodiments of the tower design in FIG. 4 and FIG. 5.

According to the embodiment in FIG. 4, the tower 31 also has a simple helix design. The towers shown once again have six sides and each side has a bottom and a top closure element, where applicable in the form of a shortened wall element 41, 42. The individual wall elements in between are tapered, wherein the bottom and top joint side are realized parallel to each other, but inclined upwards at an angle α in relation to the foundation side. The angle α, however, is selected in an advantageous manner such that it corresponds to 360° through the number of sides, so that once again where there are N sides, the N+1 wall element can once again be arranged on the first wall element of a helix section 43. The bottom and top sides of the joints of the wall element 40, in this case, form a continuous line 56.

The embodiment in FIG. 5 also represents a simple helix arrangement, wherein the embodiment in FIG. 5 differs to the embodiment in FIG. 4 in that the top and bottom sides of the wall elements 40 have three sections, which, in this case, are a first rising section 57, a horizontal section 58 connecting thereto and a second rising section 59. Overall this means that once again a continuous line 56 is formed, the ascent of which alters, however, with reference to the individual wall elements.

FIG. 6 shows a further embodiment of a tower 31 as claimed in the invention. The design of said tower comprises a multiple helix. The tower is constructed in the form of a base element 53 which stands on a foundation 32. Tower elements 54 are placed onto the base element 53. The tower is terminated by a closure element 55, on top of which the nacelle 33 or the adapter 35 is then arranged. The base element 53 has a plurality of shortened wall elements 41. The number of shortened wall elements 41 in the base element 53 represents the number of helix strands screw-connected together. If six shortened wall elements 41 are arranged in the base element 43, this means that six helix turns have been rotated into each other.

In the representation in FIG. 6 and FIG. 7, the wall elements 40 are designed as two triangles which are arranged offset by an angle to each other along a line 46. The line 46, in this case, is realized as exterior edge 46. The two triangles form part surfaces 44 and 45, as can be seen in FIG. 7. The base element 53 is shown in FIG. 8. In the current embodiment in FIG. 8, twelve shortened wall elements 41 are provided in the base element 53 such that, in total, twelve helix strands are rotated with each other. In the embodiment in FIG. 8 and FIG. 9, however, the wall element is realized as circle segment 50. The placing one on top of the other and the connecting of the individual tower elements 54 to each other or to the base element 53 is effected in an identical manner, however, irrespective of whether the wall elements are realized as a curved element or as a circle segment element. The individual tower elements 54 are either placed onto the tower element 54 or base element 53 lying below, pre-assembled with an intermediate plane 52 as shown in FIG. 9, or are mounted individually.

One type of connection connecting the individual wall elements 40 one to another, in this case, is shown in FIG. 7. The two joint surfaces 47 contacting each other in the mounted state are connected by way of a connection means, in the case of timber elements for example adhesive. In the case of steel elements, the joints can be welded. In addition, the joint surfaces can be provided with recesses 48 which are not provided over the entire width of the joint surface 47, but terminate before perforating the outside wall surface 38. FIG. 7 shows the interior surface 51 of the tower wall such that the recesses 48 are visible. Connection means 49 are inserted into the recesses 48 and are subsequently connected to the wall elements 40. The connection means 49 can be dowels or metal plates or sheets. Connecting is effected, for example, with adhesive which is injected into the recesses 48. In addition, the outside surfaces of the recess can then be masked, for example, with adhesive tape or the like. However, the connection possibilities shown in FIG. 7, such as bonding the joints and providing recesses and inserting connection means, are not restricted in this case to the multiple helix embodiment. Such embodiments can also be used with the simple helix forms, such as shown in FIGS. 2 to 5.

More possibilities for connecting the wall elements to each other are shown below in FIGS. 10 to 17.

The connection of the wall elements 40 to each other can be effected in different ways. In this case, recesses 48 are provided in each case, connection means 49 being inserted into said recesses. Said connection means are then connected to the wall elements, for example by bonding or the like, in order to create a holding operative connection. Said operative connection can then absorb shear movements and the like or the stresses resulting therefrom. A further variant is shown in FIG. 10. In this case triangular or wedge-shaped recesses 48 are provided in the wall elements 40. Adhesive can be applied to the joint surfaces 47 of the wall elements 40. The same applies to the faces 64 of the recesses 48. The connection means 49 is provided as a rhombic cuboid in the form of a dowel 61. If timber is used as the material for the wall elements 40, the dowels 61 are also wooden dowels. Said dowels 61 can either be inserted into the recesses 48 once the wall elements 40 have been positioned onto the joint surfaces 47, or the dowels 61 are inserted into the recess 48 of the already mounted wall element 40 and the wall element lying above is placed onto the dowels 61 by way of the recesses provided there and then arranged together on the joint surface 47 and locked by means of bonding or similar connection methods. The bonding is shown in FIG. 11 as adhesive 60. A more extensive representation of the wooden dowel 61 is shown in FIG. 12.

FIGS. 13 and 14 show the form of connection of the sheet elements marked out already for FIG. 7 in slots. In the embodiment in FIG. 13, recesses 48 are provided in the wall elements 40 in the form of slots, said slots being admitted into the joint surface 47, however not in a completely continuous manner from the interior surface 51 as far as the exterior surface 38 but leaving a residual wall element 65. Perforated plates 62 are inserted into the slots 48. Adhesive is once again applied onto the joint surfaces 47 and the next wall element 40 is placed with its recess 48 onto the perforated plates 62 on the wall. As an alternative to this, once again the wall elements can also be placed one on top of another and the perforated plates are inserted into the recesses 48 that are then present and, as shown in FIG. 14, are bonded with adhesive 60. The end face of the perforated plates can then be covered in its turn by an adhesive tape or another suitable covering means. This also serves, among other things, as protection against corrosion.

A further embodiment of the connection possibility is shown in FIG. 15. In this case, the joint surfaces are provided along the face with recesses 48 in the form of grooves 63 parallel to the exterior surface 38 or interior surface 51 of the wall element 40. Tongues 64 as connection means 49 are inserted into said grooves 63. The fastening of the tongues 63 in the grooves 64 is effected by means of adhesive 60. The grooves 64 of the wall element 40 which is then to be arranged thereon are placed onto the tongues 63. A further embodiment in this connection is shown in FIGS. 16 and 17. Recesses 48 in the form of a slot extending parallel to the exterior surface 38 or interior surface 51 of the wall element 40 are also provided here in the joint surfaces 47 of the wall elements 40. Elongated plates 66 as connection means 49 are inserted into the slots 48 and are also bonded to each other. A top view of the joint surfaces 47 of the wall elements 40 with inserted plates 66 is shown in FIG. 17.

FIG. 18 shows the applying of a coating 69 onto a wall element 40. A bonding device 67 is provided for this purpose, said bonding device spraying the adhesive 60 onto the tower exterior surface 38 of the wall element 40. The coating 69, which is provided as roll 68, is applied directly after the spraying. The coating 69 is rolled onto the surface moistened with adhesive by the roll 68 and consequently applied onto the surface of the wall element 40. The applying can be effected onto the individual sides 39 of the tower once the tower 31 has been constructed. As an alternative to this, each individual wall element can be directly coated before construction of an individual wall element, or the coatings are effected once the individual wall element has been attached to the tower such that the coating of the wall elements is effected in an individual manner in the mounted state. Once the coating 39 has been applied, the joints of the coating (not shown) are connected together such that the tower 31 is covered in a continuous, entire manner by the coating 69. The finished coated state is shown in FIG. 19.

FIG. 20 then shows the operating state of the wind power installation 30 and the vapor pressure gradient prevailing here, shown in the form of the moisture movement 71 and the removal of the moisture by means of heat dissipation 72. The vapor permeability of the coating 69 is less than that of the material of the wall element 40. This is especially necessary where timber is used because it ensures that moisture possibly passing through the coating 69 is removed from the transition region between coating and timber and also from the timber construction as such. The heat dissipation 72 influences the climatic conditions within the tower such that there is a water vapor gradient from outside to inside. The moisture that collects on the surface of the interior surface 51 of the tower 31 and has passed through the wall element 40 is entrained by the rising heat and is removed out of the tower 31 by said heat. The water vapor generated in this case rises and escapes from the tower. As an alternative to this or in addition to it, suction of the water vapor can also be provided. Consequently, a temperature gradient prevails in such a manner that the exterior temperature is lower than the temperature in the interior of the tower 31.

As the connections for nacelles 33 with reference to the towers 31 are realized substantially in the shape of a segment of a circle, an adapter 35 as claimed in the invention is proposed, said adapter making possible a transition between the polygonal tower 31 and the circle segment-shaped connection of the nacelle 33. For this purpose there is provided a side wall 76, at the bottom end of which is provided a flange 73 which has bores 74. The flange 73 is provided centrally with an opening 75.

The flange 73 is used for the purpose of being positioned on the polygonal joint surface 47 of the top-most section of the tower 31 and being connected to the tower by means of the bores 74. Connection regions 74 for the nacelle 33 are provided on the upper section of the side wall 46. Where applicable, it is possible for a reinforced section 78 to be provided on the side wall 76 in order to obtain better load-bearing capacity of the side wall 76.

LIST OF REFERENCES

-   30 Wind power installation -   31 Tower -   32 Foundation -   33 Nacelle -   34 Rotor -   35 Adapter -   36 Rotor blade -   37 Hub -   38 Tower exterior surface -   39 Tower side -   40 Wall element -   41 Shortened wall element -   42 Shortened wall element -   43 Helix section -   44 Part surface -   45 Part surface -   46 Edge -   47 Joint surface -   48 Recess -   49 Connection means -   50 Segment -   51 Tower interior surface -   52 Intermediate plane -   53 Base element -   54 Tower element -   55 Closure element -   56 Continuous line -   57 Rising section -   58 Horizontal section -   59 Rising section -   60 Adhesive -   61 Dowel -   62 Perforated plate -   63 Groove -   64 Tongue -   65 Residual region -   66 Plate -   67 Bonding device -   68 Roll -   69 Coating -   70 Heat dissipation -   71 Moisture movement -   72 Heat dissipation -   73 Flange -   74 Bore -   75 Opening -   76 Side wall -   77 Nacelle connection -   78 Reinforced section 

1. A tower for a wind power installation, wherein the walls of the tower are at least partially produced from individual wall sections which are produced from a wood material and are connected to one another by means of connection means, characterized in that the wall sections are arranged in a manner offset in relation to one another so as to form a helix. 2-29. (canceled)
 30. The tower as claimed in claim 1, characterized in that the helix is a simple helix or a multiple helix which is formed from a plurality of single helices.
 31. The tower as claimed in claim 30, characterized in that the number of simple helices which form the multiple helix corresponds to the number of wall sections in a horizontal plane of the tower.
 32. The tower as claimed in claim 30, characterized in that the wall section is a rhombus which is placed on end.
 33. The tower as claimed in claim 32, characterized in that the rhombus is a circle segment in the horizontal direction or the rhombus is formed by two triangles which are connected to one another in a vertical manner, wherein the surfaces of the triangles are arranged at an angle to one another, wherein in a preferred manner the angle is 360° divided by the number of simple helices.
 34. The tower as claimed in claim 1, characterized in that the upper joint sides of the individual components of a helix is a continuous line or a graduation.
 35. The tower as claimed in claim 1, characterized in that the wall sections at least partially in joints have slots which are arranged transversely to the direction of the joint or longitudinally to the direction of the joint.
 36. The tower as claimed in claim 35, characterized in that the connection means, in a preferred manner metal plates, in a particularly preferred manner perforated plates, are arranged in the slots and are preferably bonded in the slots.
 37. The tower as claimed in claim 1, characterized in that the individual wall sections are produced from as wood material wherein in a preferred manner the wood material is laminated plywood or a wood composite material.
 38. The tower as claimed in claim 1, characterized in that the tower is assembled on site from the individual wall sections.
 39. The tower as claimed in claim 1, characterized in that the surface of the exterior of the tower is provided with a coating.
 40. The tower as claimed in claim 39, characterized in that the coating absorbs at least part of the tensile stress acting on the surface of the tower and seals the surface of the exterior of the tower against the environmental influences, in particular moisture, which act on the surface from the outside.
 41. The tower as claimed in claim 39, characterized in that the coating is applied onto the surface of the exterior of the tower at least partially over the entire area.
 42. The tower as claimed in claim 39, characterized in that the coating is a laminate, a foil, a woven fabric, a plate or a textile, wherein in as preferred manner the coating is a plastics material, a plastics material plate, a woven fabric or a textile made from a plastics material, which, in a preferred manner, are produced from poly propylene, polyurethane, polyvinyl chloride, polyester, polycarbonate or polythene.
 43. The tower as claimed in claim 39, characterized in that the coating is bonded at least partially onto the tower surface, wherein in a preferred manner, the coating consists of individual sections which are connected together, in a preferred manner bonded or welded together.
 44. The tower as claimed in claim 43, characterized in that the vapor permeability of the coating is less than that of the wood material.
 45. The tower as claimed in claim 39, characterized in that a heat generator is arranged in the interior of the tower, wherein, in a preferred manner, this is the power electronics of a wind power installation.
 46. The tower as claimed in claim 39, characterized in that the support structure of the tower is constructed at least partially from materials which are not suitable for exterior use.
 47. The tower as claimed in claim 39, characterized in that the coating is applied once the tower has been constructed, or the coating is applied as the tower is being constructed, or the coating is applied before the tower is constructed, preferably on site.
 48. The tower as claimed in claim 39, characterized in that the coating is applied directly onto the wall sections of the tower. 